Fifth wheel lube plate having a perforated support member

ABSTRACT

The fifth wheel hitch lube plate ( 30 ) of the present invention comprises a perforated support member ( 40 ) having a plurality of perforations ( 50 ) and a lubricious material ( 42 ) molded around the perforated support member such that the lubricious material covers both the top and bottom surfaces of the perforated support member and extends through the perforations formed in the perforated support member. Preferably, the support member is a perforated metal plate and the lubricious material is nylon, graphite, or an ultra-high molecular weight (UHMW) polyethylene material. The problems associated with utilizing nylon (or similar materials) and bonding it to a support plate are overcome by forming the plurality of apertures in the support plate so that a mechanical cohesive bond is formed between the upper and lower surfaces of the support plate, thereby substantially increasing the lube plate strength, and shear strength, while decreasing the likelihood that the lube plate may buckle.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/286,318 filed on Apr. 25, 2001.

BACKGROUND OF THE INVENTION

The present invention generally pertains to a fifth wheel lube plate.

A common hitch for hauling large trailers is the well-known fifth wheelhitch, which has a large bifurcated bearing plate that receives akingpin and locks it in place with one or more jaws. The kingpin ismounted on a trailer, which also has a bearing plate that rests upon andpivots on the upper surface of the hitch bearing plate to enablearticulation between the trailer and its towing tractor. This pivotalaction is typically aided by a layer or film of grease on the hitchsurface. Because this grease is not only messy but also tends to retaindirt and dust, which cause wear, it is undesirable.

Various attempts have been made in the past to provide a lubricioussurface layer for the hitch without the extensive amount of greasenormally required. These efforts are believed to be largely set forth orrepresented by U.S. Pat. Nos. 5,263,856 to Huehn et al.; U.S. Pat. No.3,174,812 to Widmer; U.S. Pat. No. 3,704,924 to Lowry; U.S. Pat. No.3,275,390 to Franks; U.S. Pat. No. 5,066,035 to Athans et al.; U.S. Pat.No. 3,924,909 to Kent et al.; U.S. Pat. No. 4,121,853 to McKay; U.S.Pat. No. 4,169,635 to Szalay et al.; U.S. Pat. No. 4,457,531 to Hunger;U.S. Pat. No. 4,542,912 to St. Louis; U.S. Pat. No. 4,752,081 to Reenerset al.; U.S. Pat. No. 4,805,926 to Mamery; U.S. Pat. No. 6,010,141 toHuntimer et al.; U.S. Pat. No. 6,045,148 to Baumeister et al.; and U.S.Pat. No. 5,620,770 and U.S. Pat. No. 5,622,767 to Cork. Many of thesedesigns would require total redesign of the hitch plate. Others involvefastening devices undesirably exposed on the top of the lubriciousmaterial. Some have the lubricious layer rather permanently mounted tothe hitch so that replacement of a worn product is extremely difficultand costly. Structures such as that disclosed in U.S. Pat. No. 3,174,812require special cavities in the fifth wheel and only provide a smallbearing surface area considered inadequate. As a consequence of theseand related shortcomings, most fifth wheel hitches in use still comprisethe well-known grease-coated metal plate.

To overcome many of these problems, U.S. Pat. No. 5,522,613 issued toHeeb and commonly assigned with this application discloses a fifth wheelhitch having specially configured, interfitting lube plates mounted ontothe hitch plate so as to substantially cover a maximum area of thebearing surface yet arranged to enable each lube plate to performindependently to a degree allowing localized “stick-slip” motion betweenthe lubricious pad and the overlying trailer bearing plate. Lubriciouspolymer layer segments are disclosed that form replaceable segmentedplates that are bonded to like configured, segmented steel backingplates. Threaded studs are stud-welded to the metal backing plates,projecting only from the bottom surface thereof with the studs extendingdown through orifices in the hitch plate for securing to the hitch plateby nuts. The lubricious material disclosed in U.S. Pat. No. 5,522,613 isa nylon material reinforced with embedded glass fibers orpolytetrafluoroethylene embodied in a sintered matrix. The lubriciousmaterial is disclosed as being either molded onto the metal supportplate and bonded in situ, or applied as a prefabricated layer and bondedto the metal support plate by an adhesive.

While nylon is a satisfactory material, it is very difficult to attachto a metal plate. Thus, structures similar to that disclosed in U.S.Pat. No. 5,522,613 have been constructed utilizing urethane, which bondsbetter to the metal backing plate. While such a construction workssatisfactorily, it has been discovered some lubricious materials behavedifferently in different climates. It is desirable to utilize a materialthat is lubricious, economical and behaves satisfactorily in mostclimates.

One commercially available lube plate utilizes a relatively thick layerof fiber reinforced composite plastic. Because the lube plate utilizesonly a few fasteners to hold it to the hitch plate, it has a tendency tosled around, thereby requiring a substantial pocket in the top surfaceof the hitch plate. This lube plate is also subject to peeling orbuckling when a driver backs his tractor into the trailer and theleading edge of the trailer hits the lube plate, because the lube platematerial is not very rigid and has few fasteners.

Accordingly, there is a need for a suitable lube plate construction thatovercomes the problems noted above with respect to the prior art.Specifically, there is a need for a low cost lubricious sliding surfaceon which the trailer bolster plate articulates, that minimizes thepossibility that the plastic insert may “peel” away from the top of thefifth wheel plate.

SUMMARY OF THE INVENTION

The fifth wheel hitch lube plate of the present invention comprises aperforated support member having a plurality of perforations and alubricious material molded around the perforated support member suchthat the lubricious material covers both the top and bottom surfaces ofthe perforated support member and extends through the perforationsformed in the perforated support member. Preferably, the support memberis a perforated metal plate and the lubricious material is nylon,graphite, or an ultra-high molecular weight (UHMW) polyethylenematerial. The problems associated with utilizing nylon (or similarmaterials) and bonding it to a metal support plate are overcome byforming the plurality of apertures in the metal support plate so that amechanical cohesive bond is formed between the upper and lower surfacesof the metal support plate, thereby substantially increasing the lubeplate strength and shear strength, while decreasing the likelihood thatthe lube plate may buckle.

According to another aspect of the present invention, a fifth wheelhitch lube plate is provided that comprises a support member, alubricious material supported by the support member, and a plurality ofstuds extending downward from the support member and having a pluralityof deformable ribs that deform to allow easy insertion into a hole in afifth wheel hitch plate, while resisting removal from the hole whenpulled in a direction opposite the insertion direction.

According to another embodiment of the present invention, the fifthwheel hitch lube plate comprises a perforated metal support plate havinga plurality of perforations, and a lubricious material molded around theperforated metal support plate. The lubricious material comprising anultra-high molecular weight polyethylene material.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a top plan view of the hitch of the present inventionutilizing a two-pad arrangement;

FIG. 2 is a bottom plan view of the hitch in FIG. 1;

FIG. 3 is a top plan view of a lube plate constructed in accordance witha first embodiment of the present invention, which utilizes athrough-hole fastener such as a screw;

FIG. 4 is a side elevational view of the lube plate shown in FIG. 3;

FIG. 5 is an enlarged fragmentary, elevational, cross-sectional view ofthe lube plate shown in FIG. 3 taken along line 5–5′;

FIG. 6 is an enlarged fragmentary, elevational, cross-sectional view ofthe lube plate shown in FIG. 3 taken along line 6–6′ showing thethrough-hole fastener;

FIG. 7 is a top plan view of a perforated metal support member used inthe lube plate of a second embodiment of the present invention, whichutilizes studs;

FIG. 8 is a side elevational view of the perforated metal support membershown in FIG. 7;

FIG. 9 is an enlarged fragmentary, elevational, cross-sectional view ofthe hitch shown in FIGS. 1 and 2;

FIG. 10 is an enlarged, fragmentary, elevational, cross-sectional viewcomparable to FIG. 9, but with the lube plate structure of the secondembodiment mounted thereon;

FIG. 11 is a top plan view of a lube plate structure constructed inaccordance with a third embodiment of the present invention, whichutilizes a novel punch-through fastener;

FIGS. 12A–12C are enlarged, fragmentary, elevational, cross-sectionalviews showing the detachment of the lube plate shown in FIG. 11 from ahitch plate; and

FIG. 13 is top plan view of a perforated support member constructed inaccordance with a fourth embodiment of the present invention, whichutilizes weld tabs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now specifically to the drawings, the fifth wheel hitchassembly 10 depicted in FIGS. 1, 2, 9, and 10 comprises a fifth wheelhitch plate 12 having a bifurcated rear portion which forms laterallyspaced ramps 14 astraddle a kingpin receiving mouth 16 and throat 18. Inthe hitch shown, a jaw 19 is mounted on a pivot pin 20 to pivot thereonand lock a conventional depending kingpin (not shown) on a trailerwithin throat 18 until purposely released. This hitch has an upstandingperipheral rim 12′ extending around both sides and the forward end ofthe hitch, defining a pocket 12″ (FIG. 9) in the top of the hitch plate.A lower, transverse reinforcing beam 20 a extends across the mouth 16below the level of the entering kingpin in conventional fashion. Theopposite sides of plate 12 are mounted on bearing trumons 22 inconventional fashion to pivot forwardly and rearwardly on a transversepivot axis. Hitch plate 12 has an overall pattern of orifices 24 (FIG.9) extending through the thickness of the plate.

Shown in FIG. 1 to be mounted on hitch plate 12 are specially configuredand cooperative lube plates 30 disposed on opposite lateral sides of themouth and throat of the hitch plate. The two lube plates 30 arebasically in mirror-image relationship, having the same arcuatecurvilinear configuration which arcs around the mouth and throat areaand radially extends to the outer edge of pocket 12″, i.e., out to rim12′. The pocket and the two lube plates cover a substantial portion ofthe fifth wheel hitch plate.

As best shown in FIGS. 3–8, each of the lube plates 30 depicted includesa perforated support member 40 having an upper surface and a lowersurface. Molded around support member 40 is a lubricious material 42.Support member 40 is preferably a perforated steel plate of rolled steelhaving a thickness within the range of about 0.030 to 0.125 inch. Thesupport member 40 includes a plurality of circular perforations 50defining apertures extending between the upper and lower surface ofmember 40.

In the structure shown in FIGS. 5 and 7, perforations 50 are formedthroughout the surface area of support member 40 with the exception ofregions surrounding that from which a stud 44 extends. The radialminimum distance from the center of the stud to the edge of theperforations 50 formed in support member 40 and the size, number, andspacing of the perforations depend upon the lubricious material used andthe metal backing plate material used and their strengthcharacteristics. Perforations 50 are preferably sufficiently small toensure the structural integrity of support member 40 while beingsufficiently numerous to allow good mechanical bonding between thelayers of material 42 on the upper and lower surfaces of support member40.

The lubricious material 42 may be formed of nylon, graphite, ultrahighmolecular weight (UHMW) polyethylene, or any other suitableanti-friction material. Most preferably, lubricious material 42 ismodified nylon with an ultraviolet protectant stabilizer or UHMWpolyethylene. The nylon may be formed about support member 40 byinjection molding. If UHMW polyethylene is utilized, the material may bemolded onto support member 40 by compression molding.

In a preferred embodiment, the thickness of the lubricious material thatextends below support member 40 is less than the thickness of thematerial above the upper surface of support member 40. As shown in FIG.3, the edges of plate 30 are preferably beveled and a pair of grooves 52is formed in the upper surface to aid in the collection of debris thatmay otherwise collect between the upper surface of lube plate 30 and thebearing plate on the trailer.

Preferably, the lube plate 30 is formed slightly convex towards itsupper surface. This allows a thinner support member 40 to be utilizedwhile retaining the strength of the lube plate 30. Thus, the overallthickness of the lube plate may be reduced, which may allow for theelimination of the pocket 12″ (FIG. 9) in the hitch plate 12. Theperforated metal plate may be made thicker than the prior artnon-perforated metal plate without added extra weight. Thus, theperforated plate of the present invention adds to the strength of thelube plate without adding extra weight. The inventive lube plate is alsoless likely to curl up, and the lubricious material is less likely to betorn off the support member. The perforated plate also spreads out theforce of impact over a larger area on the hitch plate thus allowing theuse of fewer attachments to the hitch plate.

According to the first embodiment shown in FIGS. 3–6, the lube platesmay be attached to the fifth wheel hitch plate using through-holefasteners such as the tapered screws 44 a shown in FIGS. 3–6.

According to a second embodiment shown in FIGS. 7, 8, and 10, aplurality of threaded studs 44 b are stud-welded at their upper ends tothe bottom surface of support member 40 as shown in FIGS. 8 and 10 orare pressed into the support plate with their heads flush with the topof the support plate. These studs are positioned in a pattern on theindividual support members corresponding to portions of the overallpattern of orifices 24 in support member 12 to enable the studs toproject down through the hitch plate for securing by a washer 46 and nut48 on each stud (see FIGS. 2 and 10).

The two lube plates require only one mold configuration to form themsince the lube plates 30 are simply the inverted forms of each other andthose one part may be used for the right and left lube plates.Alternatively, the right and left lube plates may be different from oneanother.

Mounting of the lube plates is simple, namely placing the two plates inposition with the studs 44 extending down through the openings andfastening the nuts 48 in position to retain them on the hitch plate.Replacement of the lube plates, either individually or collectively, isalso easy to accomplish by removing nuts 48 from studs 44 b, lifting anyworn pad subassemblies from the hitch plate, and replacing them with newones.

The peripheral rim 12′ enables the lube plates and rim to withstandexcessive vertical downward loads, excessive shear loads, and/ortorsional loads, yet each lube plate is able to perform independently inthe surface-to-surface relationship with the overlying trailer bearingplate to a degree enabling localized “stick-slip” motion characteristicsof friction relationship between the polymer of the lube plate surfaceand the metal of the overlying trailer bearing plate.

According to a third, alternative embodiment shown in FIGS. 11 and12A–12C, studs 144 are utilized that have “one-way” flexible rings ortabs that bend when inserted into a hole in the hitch plate and resistmovement in the opposite direction by biting into the sides of the hole.This allows the lube plates 130 to be installed from the top of thehitch plate without requiring removal of the hitch plate from the hitchmounting brackets and without need for nuts and washers to be attachedat the bottom of the hitch plate. To remove the lube plates 130 from thehitch plate, one may use a punch 100 to punch out the studs from the topside of the lube and hitch plates once again eliminating the need toremove to the hitch plate from its mounting brackets as would berequired to remove any nuts and washers. These novel studs may be usedwith any lube plate construction whether perforated or non-perforated.

According to a fourth embodiment shown in FIG. 13, support member 240may include a plurality of tabs 244 that may be welded or otherwisesecured onto the hitch plate.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove are merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including thedoctrine of equivalents.

1. A fifth wheel hitch lube plate comprising: a perforated supportmember having a plurality of perforations; and a lubricious materialmolded around said perforated support member such that said lubriciousmaterial covers both the top and bottom surfaces of said perforatedsupport member and extends through said perforations formed in saidperforated support member.
 2. The fifth wheel hitch lube plate of claim1, wherein said perforated support member is a perforated metal plate.3. The fifth wheel hitch lube plate of claim 1, wherein said lubriciousmaterial is any one or combination of nylon, graphite, and an ultra-highmolecular weight polyethylene material.
 4. The fifth wheel hitch lubeplate of claim 1, wherein said perforated support member comprises aplurality of studs extending downward from said support member andhaving a plurality of deformable ribs that deform to allow easyinsertion into a hole in a fifth wheel hitch plate, while resistingremoval from the hole when pulled in a direction opposite the insertiondirection.
 5. The fifth wheel hitch lube plate of claim 1, wherein saidperforated support member has a thickness within the range of about0.030 to 0.125 inch.
 6. A lube plate for attachment to a hitch plate ofa fifth wheel hitch, said lube plate comprising: a support member; alubricious material supported by said support member; and a plurality ofstuds extending downward from said support member and having a pluralityof deformable ribs that deform to allow easy insertion into a hole inthe fifth wheel hitch plate, while resisting removal from the hole whenpulled in a direction opposite the insertion direction.
 7. The fifthwheel hitch lube plate of claim 6, wherein said support member has aplurality of perforations, and wherein said lubricious material ismolded around said perforated support member such that said lubriciousmaterial covers both the top and bottom surfaces of said perforatedsupport member and extends through said perforations formed in saidperforated support member.
 8. The fifth wheel hitch lube plate of claim7, wherein said perforated support member is a perforated metal plate.9. The fifth wheel hitch lube plate of claim 6, wherein said lubriciousmaterial is any one or combination of nylon, graphite, and an ultra-highmolecular weight polyethylene material.
 10. The fifth wheel hitch lubeplate of claim 6, wherein said support member has a thickness within therange of about 0.030 to 0.125 inch.
 11. The fifth wheel hitch lube plateof claim 6, wherein each of said studs is generally cylindrical inshape.
 12. The fifth wheel hitch lube plate of claim 6, wherein each ofsaid studs is configured to allow the lube plate to be mounted to thefifth wheel hitch plate without requiring any additional fasteners. 13.The fifth wheel hitch lube plate of claim 6, wherein each of said studsis configured to allow removal of the lube plate to be mounted to thefifth wheel hitch plate by punching the stud through the hole of thefifth wheel hitch plate in the direction of insertion.
 14. A lube platefor attachment to a hitch plate of a fifth wheel hitch, said lube platecomprising: a perforated metal support plate having a plurality ofperforations; and a lubricious material molded around said perforatedmetal support plate, said lubricious material comprising an ultra-highmolecular weight polyethylene material, wherein said perforated metalsupport plate comprises a plurality of studs extending downward fromsaid metal support plate and having a plurality of deformable ribs thatdeform to allow easy insertion into a hole in a fifth wheel hitch plate,while resisting removal from the hole when pulled in a directionopposite the insertion direction.